Inflatable game balls are balls such as volleyballs, basketballs, footballs and softballs, which are pressurized for use. Other inflatable composite articles are boat buoys, flotation gear and the like.
Inflatable game balls as well as other kinds of inflatable composite articles have been variously made and covered by rotocasting, plastisol flooding, plastisol dipping, vacuum forming and application of individual panels. The difficulties with such manufacturing techniques have been that they do not provide a covering of uniform thickness over the surface of the ball. It is essential to the quality of game balls as well as certain other inflatable composite articles that the covering be molded to a thickness as uniform as possible.
Electrostatic spraying and coating of molds with molding materials has been variously utilized in molding. The technique provides for uniform and selective application of molding material over the surfaces of the mold and in turn molded articles of uniform thickness. Exemplary of the art is believed to be U.S. Pats. No. 3,182,103, No. 3,374,500, No. 3,408,432, No. 3,478,387, No. 3,491,170, No. 3,504,063, No. 3,607,998 and No. 3,660,547. Such electrostatic techniques have not been adapted to provide for the covering of inflatable composite articles and particularly inflatable game balls with coverings of substantially uniform thickness.
Inflatable inner molds have been utilized in molding and forming plastic articles that have constricted openings, such as milk bottles and Christmas tree ornaments. Such inflatable molds provide for the making of such hollow bodies in one piece, rather than in two or more pieces followed by assembly. Illustrative of the disclosures utilizing inflatable molds are believed to be those set forth in U.S. Pats. No. 3,530,208 and No. 3,607,998. Such inflatable molds have not heretofore been adapted to provide composite articles and particularly inflatable composite articles with coverings of substantially uniform thickness. Other somewhat related disclosures are set forth in U.S. Pats. No. 2,614,955, No. 3,135,640 and No. 3,151,196.